Implant Technology Unit 5 Flashcards
(154 cards)
when is joint replacement in the upper limb indicated
after other forms of conservative treatment have failed i.e. NSAIDs, injections
what is the primary and secondary aim of upper limb joint replacement
primary
- eliminate pain
secondary
- restore function to the particularly joint being replaced w/ a view of restoring overall functions of the hand
patients w/ RA often have several joints affected by the disease and require individual Tx plans - a problem w/ the spine or lower limb that require surgery is given priority over a problem in the upper limb, why?
- RA of the cervical spine causes instability and can be associated w/ significant or progressive neuro Sx.
- Needs to be addressed to prevent permanent damage
- successful replacement of hip and knee will lessen/eliminate need for upper limb to support BW during walking
- if these loads are not reduced/eliminated they could potentially compromise success of the surgery
if several upper limb joints are affected, and all joints are equally affected by pain, then as a general rule what order with joint replacements usually be performed
distally to proximally
i.e. fingers first, wrist, elbow and finally the shoulder
what is the reasoning for some surgeons working distal to proximal
- primary objective of upper limb joint replacement, after pain relief, is to allow restoration of hand function
- impairments in distal joints may compromise the critical, early physiotherapy necessary following the replacement of a more proximal joint
- arguable that more functional improvement is gained the more distal the joint
some surgery prefer to replace the shoulder however, before other distal joints, what are the reasons for this
- shoulder pain is more troublesome at night and may radiate to the elbows
- an immobile shoulder will cause abnormal loadings at the elbow which may lead to early failure of an elbow prosthesis
- rehab of the other upper limb joints can be simplified with a pain free or near pain free shoulder
what is the general criteria for upper limb joint replacements
- tolerate by human body w/ no short term and little long term risk
- relieve pain and achieve sufficient mobility for activities of daily living
- function w/out failure, ideally should last the expected life span of the individual patient
- insertion w/ predictable outcome guaranteed by competent surgeon
- cost effective
what is unexpected about the different between a total and hemi-arthroplasty in shoulder replacements
get better pain relief and ROM w/ total arthroplasty as opposed to hemi-arthroplasty
what is proving to be the superior joint replacements in the upper limb
shoulder joint replacements are proving to be more successful in survival terms
[followed by elbow, then wrist, then fingers]
what are 6 materials used in upper limb joint replacements
stainless steel titanium titanium alloys cobalt chrome alloys polyethylene (usually UHDP) silicone elastomer
how often is shoulder replacements done
they are now the third most common arthroplastic procedure after hip and knee joint replacement
what is 1 way designs of shoulder prostheses are divided and what are these categories
divided according to the amount of movement constraint
1 - unconstrained e.g. Neer Prosthesis
2 - semiconstrained e.g. Gristina prosthesis
3 - constrained e.g. Michael Reese prosthesis
what is another way designs of shoulder prostheses are divided
may also be divided according to whether or not they conform to anatomy of the normal joint
1 - reversed or inverted anatomy design
- called as such as the humeral component is a socket instead of a ball
- e.g. Cavendish prothesis
what is the aim of most shoulder joint replacements
pain relief
improvements in ROM and function
most patients have RA or OA
what is the success rates of shoulder replacements
almost 90% have no or only slight pain after a total shoulder replacement
patients generally achieve around 90 to 135 abduction w/ unconstrained designs
what will the type of shoulder replacement design used depend on
quality of the soft tissue that surround the shoulder joint and provide joint stability
patients will undergo preoperative assessment of ROM, strength, stability and function to determine the exact nature of their problems
what shoulder replacement design will be used if the rotator cuff is intact and functioning
unconstrained prosthesis
what shoulder replacement design will be used if there is little or no stability provided by soft tissue
constrained design
what is the primary function of the shoulder
allow the hand to be positioned in space
what are the 3 synovial joints that make up the shoulder joint and 1 important articulation
3 joints
- glenohumeral, acromioclavicular and sternoclavicular
1 articulation
- scapulothoracic bone-on-muscle-on-bone articulation
what is the most important synovial joint in the shoulder which is the joint that is replaced in a total shoulder replacement
the glenohumeral joint
- as it has the largest ROM and most load bearing
- forces here can be as high as several times BW which a prosthetic must be able to withstand
what makes the shoulder joint very mobile but also very unstable
[what exists to make the shoulder more stable]
the shallow glenoid fossa
[the rotator cuff and other soft tissues]
what needs to be taken into consideration when the bone stock is removed during a TSR
that soft tissue attachments are preserved
[scapula is a thin bit of bone so there is only limited amount of bone stock to which a prosthetic can be attached]
what problems does the thin nature of the scapula cause
loosening of the glenoid component, especially w/ constrained design